/*
 * ispqueue.c
 *
 * TI OMAP3 ISP - Video buffers queue handling
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 *           Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <asm/cacheflush.h>
#include <linux/dma-mapping.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include "ispqueue.h"

/* -----------------------------------------------------------------------------
 * Video buffers management
 */

/*
 * isp_video_buffer_cache_sync - Keep the buffers coherent between CPU and ISP
 *
 * The typical operation required here is Cache Invalidation across
 * the (user space) buffer address range. And this _must_ be done
 * at QBUF stage (and *only* at QBUF).
 *
 * We try to use optimal cache invalidation function:
 * - dmac_map_area:
 *    - used when the number of pages are _low_.
 *    - it becomes quite slow as the number of pages increase.
 *       - for 648x492 viewfinder (150 pages) it takes 1.3 ms.
 *       - for 5 Mpix buffer (2491 pages) it takes between 25-50 ms.
 *
 * - flush_cache_all:
 *    - used when the number of pages are _high_.
 *    - time taken in the range of 500-900 us.
 *    - has a higher penalty but, as whole dcache + icache is invalidated
 */
/*
 * FIXME: dmac_inv_range crashes randomly on the user space buffer
 *        address. Fall back to flush_cache_all for now.
 */
#define ISP_CACHE_FLUSH_PAGES_MAX       0

static void isp_video_buffer_cache_sync(struct isp_video_buffer *buf)
{
        if (buf->skip_cache)
                return;

        if (buf->vbuf.m.userptr == 0 || buf->npages == 0 ||
            buf->npages > ISP_CACHE_FLUSH_PAGES_MAX)
                flush_cache_all();
        else {
                dmac_map_area((void *)buf->vbuf.m.userptr, buf->vbuf.length,
                              DMA_FROM_DEVICE);
                outer_inv_range(buf->vbuf.m.userptr,
                                buf->vbuf.m.userptr + buf->vbuf.length);
        }
}

/*
 * isp_video_buffer_lock_vma - Prevent VMAs from being unmapped
 *
 * Lock the VMAs underlying the given buffer into memory. This avoids the
 * userspace buffer mapping from being swapped out, making VIPT cache handling
 * easier.
 *
 * Note that the pages will not be freed as the buffers have been locked to
 * memory using by a call to get_user_pages(), but the userspace mapping could
 * still disappear if the VMAs are not locked. This is caused by the memory
 * management code trying to be as lock-less as possible, which results in the
 * userspace mapping manager not finding out that the pages are locked under
 * some conditions.
 */
static int isp_video_buffer_lock_vma(struct isp_video_buffer *buf, int lock)
{
        struct vm_area_struct *vma;
        unsigned long start;
        unsigned long end;
        int ret = 0;

        if (buf->vbuf.memory == V4L2_MEMORY_MMAP)
                return 0;

        /* We can be called from workqueue context if the current task dies to
         * unlock the VMAs. In that case there's no current memory management
         * context so unlocking can't be performed, but the VMAs have been or
         * are getting destroyed anyway so it doesn't really matter.
         */
        if (!current || !current->mm)
                return lock ? -EINVAL : 0;

        start = buf->vbuf.m.userptr;
        end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

        down_write(&current->mm->mmap_sem);
        spin_lock(&current->mm->page_table_lock);

        do {
                vma = find_vma(current->mm, start);
                if (vma == NULL) {
                        ret = -EFAULT;
                        goto out;
                }

                if (lock)
                        vma->vm_flags |= VM_LOCKED;
                else
                        vma->vm_flags &= ~VM_LOCKED;

                start = vma->vm_end + 1;
        } while (vma->vm_end < end);

        if (lock)
                buf->vm_flags |= VM_LOCKED;
        else
                buf->vm_flags &= ~VM_LOCKED;

out:
        spin_unlock(&current->mm->page_table_lock);
        up_write(&current->mm->mmap_sem);
        return ret;
}

/*
 * isp_video_buffer_sglist_kernel - Build a scatter list for a vmalloc'ed buffer
 *
 * Iterate over the vmalloc'ed area and create a scatter list entry for every
 * page.
 */
static int isp_video_buffer_sglist_kernel(struct isp_video_buffer *buf)
{
        struct scatterlist *sglist;
        unsigned int npages;
        unsigned int i;
        void *addr;

        addr = buf->vaddr;
        npages = PAGE_ALIGN(buf->vbuf.length) >> PAGE_SHIFT;

        sglist = vmalloc(npages * sizeof(*sglist));
        if (sglist == NULL)
                return -ENOMEM;

        sg_init_table(sglist, npages);

        for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
                struct page *page = vmalloc_to_page(addr);

                if (page == NULL || PageHighMem(page)) {
                        vfree(sglist);
                        return -EINVAL;
                }

                sg_set_page(&sglist[i], page, PAGE_SIZE, 0);
        }

        buf->sglen = npages;
        buf->sglist = sglist;

        return 0;
}

/*
 * isp_video_buffer_sglist_user - Build a scatter list for a userspace buffer
 *
 * Walk the buffer pages list and create a 1:1 mapping to a scatter list.
 */
static int isp_video_buffer_sglist_user(struct isp_video_buffer *buf)
{
        struct scatterlist *sglist;
        unsigned int offset = buf->offset;
        unsigned int i;

        sglist = vmalloc(buf->npages * sizeof(*sglist));
        if (sglist == NULL)
                return -ENOMEM;

        sg_init_table(sglist, buf->npages);

        for (i = 0; i < buf->npages; ++i) {
                if (PageHighMem(buf->pages[i])) {
                        vfree(sglist);
                        return -EINVAL;
                }

                sg_set_page(&sglist[i], buf->pages[i], PAGE_SIZE - offset,
                            offset);
                offset = 0;
        }

        buf->sglen = buf->npages;
        buf->sglist = sglist;

        return 0;
}

/*
 * isp_video_buffer_sglist_pfnmap - Build a scatter list for a VM_PFNMAP buffer
 *
 * Create a scatter list of physically contiguous pages starting at the buffer
 * memory physical address.
 */
static int isp_video_buffer_sglist_pfnmap(struct isp_video_buffer *buf)
{
        struct scatterlist *sglist;
        unsigned int offset = buf->offset;
        unsigned long pfn = buf->paddr >> PAGE_SHIFT;
        unsigned int i;

        sglist = vmalloc(buf->npages * sizeof(*sglist));
        if (sglist == NULL)
                return -ENOMEM;

        sg_init_table(sglist, buf->npages);

        for (i = 0; i < buf->npages; ++i, ++pfn) {
                sg_set_page(&sglist[i], pfn_to_page(pfn), PAGE_SIZE - offset,
                            offset);
                /* PFNMAP buffers will not get DMA-mapped, set the DMA address
                 * manually.
                 */
                sg_dma_address(&sglist[i]) = (pfn << PAGE_SHIFT) + offset;
                offset = 0;
        }

        buf->sglen = buf->npages;
        buf->sglist = sglist;

        return 0;
}

/*
 * isp_video_buffer_cleanup - Release pages for a userspace VMA.
 *
 * Release pages locked by a call isp_video_buffer_prepare_user and free the
 * pages table.
 */
static void isp_video_buffer_cleanup(struct isp_video_buffer *buf)
{
        enum dma_data_direction direction;
        unsigned int i;

        if (buf->queue->ops->buffer_cleanup)
                buf->queue->ops->buffer_cleanup(buf);

        if (!(buf->vm_flags & VM_PFNMAP)) {
                direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
                          ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
                dma_unmap_sg(buf->queue->dev, buf->sglist, buf->sglen,
                             direction);
        }

        vfree(buf->sglist);
        buf->sglist = NULL;
        buf->sglen = 0;

        if (buf->pages != NULL) {
                isp_video_buffer_lock_vma(buf, 0);

                for (i = 0; i < buf->npages; ++i)
                        page_cache_release(buf->pages[i]);

                vfree(buf->pages);
                buf->pages = NULL;
        }

        buf->npages = 0;
        buf->skip_cache = false;
}

/*
 * isp_video_buffer_prepare_user - Pin userspace VMA pages to memory.
 *
 * This function creates a list of pages for a userspace VMA. The number of
 * pages is first computed based on the buffer size, and pages are then
 * retrieved by a call to get_user_pages.
 *
 * Pages are pinned to memory by get_user_pages, making them available for DMA
 * transfers. However, due to memory management optimization, it seems the
 * get_user_pages doesn't guarantee that the pinned pages will not be written
 * to swap and removed from the userspace mapping(s). When this happens, a page
 * fault can be generated when accessing those unmapped pages.
 *
 * If the fault is triggered by a page table walk caused by VIPT cache
 * management operations, the page fault handler might oops if the MM semaphore
 * is held, as it can't handle kernel page faults in that case. To fix that, a
 * fixup entry needs to be added to the cache management code, or the userspace
 * VMA must be locked to avoid removing pages from the userspace mapping in the
 * first place.
 *
 * If the number of pages retrieved is smaller than the number required by the
 * buffer size, the function returns -EFAULT.
 */
static int isp_video_buffer_prepare_user(struct isp_video_buffer *buf)
{
        unsigned long data;
        unsigned int first;
        unsigned int last;
        int ret;

        data = buf->vbuf.m.userptr;
        first = (data & PAGE_MASK) >> PAGE_SHIFT;
        last = ((data + buf->vbuf.length - 1) & PAGE_MASK) >> PAGE_SHIFT;

        buf->offset = data & ~PAGE_MASK;
        buf->npages = last - first + 1;
        buf->pages = vmalloc(buf->npages * sizeof(buf->pages[0]));
        if (buf->pages == NULL)
                return -ENOMEM;

        down_read(&current->mm->mmap_sem);
        ret = get_user_pages(current, current->mm, data & PAGE_MASK,
                             buf->npages,
                             buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE, 0,
                             buf->pages, NULL);
        up_read(&current->mm->mmap_sem);

        if (ret != buf->npages) {
                buf->npages = ret < 0 ? 0 : ret;
                isp_video_buffer_cleanup(buf);
                return -EFAULT;
        }

        ret = isp_video_buffer_lock_vma(buf, 1);
        if (ret < 0)
                isp_video_buffer_cleanup(buf);

        return ret;
}

/*
 * isp_video_buffer_prepare_pfnmap - Validate a VM_PFNMAP userspace buffer
 *
 * Userspace VM_PFNMAP buffers are supported only if they are contiguous in
 * memory and if they span a single VMA.
 *
 * Return 0 if the buffer is valid, or -EFAULT otherwise.
 */
static int isp_video_buffer_prepare_pfnmap(struct isp_video_buffer *buf)
{
        struct vm_area_struct *vma;
        unsigned long prev_pfn;
        unsigned long this_pfn;
        unsigned long start;
        unsigned long end;
        dma_addr_t pa;
        int ret = -EFAULT;

        start = buf->vbuf.m.userptr;
        end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

        buf->offset = start & ~PAGE_MASK;
        buf->npages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
        buf->pages = NULL;

        down_read(&current->mm->mmap_sem);
        vma = find_vma(current->mm, start);
        if (vma == NULL || vma->vm_end < end)
                goto done;

        for (prev_pfn = 0; start <= end; start += PAGE_SIZE) {
                ret = follow_pfn(vma, start, &this_pfn);
                if (ret)
                        goto done;

                if (prev_pfn == 0)
                        pa = this_pfn << PAGE_SHIFT;
                else if (this_pfn != prev_pfn + 1) {
                        ret = -EFAULT;
                        goto done;
                }

                prev_pfn = this_pfn;
        }

        buf->paddr = pa + buf->offset;
        ret = 0;

done:
        up_read(&current->mm->mmap_sem);
        return ret;
}

/*
 * isp_video_buffer_prepare_vm_flags - Get VMA flags for a userspace address
 *
 * This function locates the VMAs for the buffer's userspace address and checks
 * that their flags match. The only flag that we need to care for at the moment
 * is VM_PFNMAP.
 *
 * The buffer vm_flags field is set to the first VMA flags.
 *
 * Return -EFAULT if no VMA can be found for part of the buffer, or if the VMAs
 * have incompatible flags.
 */
static int isp_video_buffer_prepare_vm_flags(struct isp_video_buffer *buf)
{
        struct vm_area_struct *vma;
        pgprot_t vm_page_prot;
        unsigned long start;
        unsigned long end;
        int ret = -EFAULT;

        start = buf->vbuf.m.userptr;
        end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

        down_read(&current->mm->mmap_sem);

        do {
                vma = find_vma(current->mm, start);
                if (vma == NULL)
                        goto done;

                if (start == buf->vbuf.m.userptr) {
                        buf->vm_flags = vma->vm_flags;
                        vm_page_prot = vma->vm_page_prot;
                }

                if ((buf->vm_flags ^ vma->vm_flags) & VM_PFNMAP)
                        goto done;

                if (vm_page_prot != vma->vm_page_prot)
                        goto done;

                start = vma->vm_end + 1;
        } while (vma->vm_end < end);

        /* Skip cache management to enhance performances for non-cached or
         * write-combining buffers.
         */
        if (vm_page_prot == pgprot_noncached(vm_page_prot) ||
            vm_page_prot == pgprot_writecombine(vm_page_prot))
                buf->skip_cache = true;

        ret = 0;

done:
        up_read(&current->mm->mmap_sem);
        return ret;
}

/*
 * isp_video_buffer_prepare - Make a buffer ready for operation
 *
 * Preparing a buffer involves:
 *
 * - validating VMAs (userspace buffers only)
 * - locking pages and VMAs into memory (userspace buffers only)
 * - building page and scatter-gather lists
 * - mapping buffers for DMA operation
 * - performing driver-specific preparation
 *
 * The function must be called in userspace context with a valid mm context
 * (this excludes cleanup paths such as sys_close when the userspace process
 * segfaults).
 */
static int isp_video_buffer_prepare(struct isp_video_buffer *buf)
{
        enum dma_data_direction direction;
        int ret;

        switch (buf->vbuf.memory) {
        case V4L2_MEMORY_MMAP:
                ret = isp_video_buffer_sglist_kernel(buf);
                break;

        case V4L2_MEMORY_USERPTR:
                ret = isp_video_buffer_prepare_vm_flags(buf);
                if (ret < 0)
                        return ret;

                if (buf->vm_flags & VM_PFNMAP) {
                        ret = isp_video_buffer_prepare_pfnmap(buf);
                        if (ret < 0)
                                return ret;

                        ret = isp_video_buffer_sglist_pfnmap(buf);
                } else {
                        ret = isp_video_buffer_prepare_user(buf);
                        if (ret < 0)
                                return ret;

                        ret = isp_video_buffer_sglist_user(buf);
                }
                break;

        default:
                return -EINVAL;
        }

        if (ret < 0)
                goto done;

        if (!(buf->vm_flags & VM_PFNMAP)) {
                direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
                          ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
                ret = dma_map_sg(buf->queue->dev, buf->sglist, buf->sglen,
                                 direction);
                if (ret != buf->sglen) {
                        ret = -EFAULT;
                        goto done;
                }
        }

        if (buf->queue->ops->buffer_prepare)
                ret = buf->queue->ops->buffer_prepare(buf);

done:
        if (ret < 0) {
                isp_video_buffer_cleanup(buf);
                return ret;
        }

        return ret;
}

/*
 * isp_video_queue_query - Query the status of a given buffer
 *
 * Locking: must be called with the queue lock held.
 */
static void isp_video_buffer_query(struct isp_video_buffer *buf,
                                   struct v4l2_buffer *vbuf)
{
        memcpy(vbuf, &buf->vbuf, sizeof(*vbuf));

        if (buf->vma_use_count)
                vbuf->flags |= V4L2_BUF_FLAG_MAPPED;

        switch (buf->state) {
        case ISP_BUF_STATE_ERROR:
                vbuf->flags |= V4L2_BUF_FLAG_ERROR;
        case ISP_BUF_STATE_DONE:
                vbuf->flags |= V4L2_BUF_FLAG_DONE;
        case ISP_BUF_STATE_QUEUED:
        case ISP_BUF_STATE_ACTIVE:
                vbuf->flags |= V4L2_BUF_FLAG_QUEUED;
                break;
        case ISP_BUF_STATE_IDLE:
        default:
                break;
        }
}

/*
 * isp_video_buffer_wait - Wait for a buffer to be ready
 *
 * In non-blocking mode, return immediately with 0 if the buffer is ready or
 * -EAGAIN if the buffer is in the QUEUED or ACTIVE state.
 *
 * In blocking mode, wait (interruptibly but with no timeout) on the buffer wait
 * queue using the same condition.
 */
static int isp_video_buffer_wait(struct isp_video_buffer *buf, int nonblocking)
{
        if (nonblocking) {
                return (buf->state != ISP_BUF_STATE_QUEUED &&
                        buf->state != ISP_BUF_STATE_ACTIVE)
                        ? 0 : -EAGAIN;
        }

        return wait_event_interruptible(buf->wait,
                buf->state != ISP_BUF_STATE_QUEUED &&
                buf->state != ISP_BUF_STATE_ACTIVE);
}

/* -----------------------------------------------------------------------------
 * Queue management
 */

/*
 * isp_video_queue_free - Free video buffers memory
 *
 * Buffers can only be freed if the queue isn't streaming and if no buffer is
 * mapped to userspace. Return -EBUSY if those conditions aren't statisfied.
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_free(struct isp_video_queue *queue)
{
        unsigned int i;

        if (queue->streaming)
                return -EBUSY;

        for (i = 0; i < queue->count; ++i) {
                if (queue->buffers[i]->vma_use_count != 0)
                        return -EBUSY;
        }

        for (i = 0; i < queue->count; ++i) {
                struct isp_video_buffer *buf = queue->buffers[i];

                isp_video_buffer_cleanup(buf);

                vfree(buf->vaddr);
                buf->vaddr = NULL;

                kfree(buf);
                queue->buffers[i] = NULL;
        }

        INIT_LIST_HEAD(&queue->queue);
        queue->count = 0;
        return 0;
}

/*
 * isp_video_queue_alloc - Allocate video buffers memory
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_alloc(struct isp_video_queue *queue,
                                 unsigned int nbuffers,
                                 unsigned int size, enum v4l2_memory memory)
{
        struct isp_video_buffer *buf;
        unsigned int i;
        void *mem;
        int ret;

        /* Start by freeing the buffers. */
        ret = isp_video_queue_free(queue);
        if (ret < 0)
                return ret;

        /* Bail out of no buffers should be allocated. */
        if (nbuffers == 0)
                return 0;

        /* Initialize the allocated buffers. */
        for (i = 0; i < nbuffers; ++i) {
                buf = kzalloc(queue->bufsize, GFP_KERNEL);
                if (buf == NULL)
                        break;

                if (memory == V4L2_MEMORY_MMAP) {
                        /* Allocate video buffers memory for mmap mode. Align
                         * the size to the page size.
                         */
                        mem = vmalloc_32_user(PAGE_ALIGN(size));
                        if (mem == NULL) {
                                kfree(buf);
                                break;
                        }

                        buf->vbuf.m.offset = i * PAGE_ALIGN(size);
                        buf->vaddr = mem;
                }

                buf->vbuf.index = i;
                buf->vbuf.length = size;
                buf->vbuf.type = queue->type;
                buf->vbuf.field = V4L2_FIELD_NONE;
                buf->vbuf.memory = memory;

                buf->queue = queue;
                init_waitqueue_head(&buf->wait);

                queue->buffers[i] = buf;
        }

        if (i == 0)
                return -ENOMEM;

        queue->count = i;
        return nbuffers;
}

/**
 * omap3isp_video_queue_cleanup - Clean up the video buffers queue
 * @queue: Video buffers queue
 *
 * Free all allocated resources and clean up the video buffers queue. The queue
 * must not be busy (no ongoing video stream) and buffers must have been
 * unmapped.
 *
 * Return 0 on success or -EBUSY if the queue is busy or buffers haven't been
 * unmapped.
 */
int omap3isp_video_queue_cleanup(struct isp_video_queue *queue)
{
        return isp_video_queue_free(queue);
}

/**
 * omap3isp_video_queue_init - Initialize the video buffers queue
 * @queue: Video buffers queue
 * @type: V4L2 buffer type (capture or output)
 * @ops: Driver-specific queue operations
 * @dev: Device used for DMA operations
 * @bufsize: Size of the driver-specific buffer structure
 *
 * Initialize the video buffers queue with the supplied parameters.
 *
 * The queue type must be one of V4L2_BUF_TYPE_VIDEO_CAPTURE or
 * V4L2_BUF_TYPE_VIDEO_OUTPUT. Other buffer types are not supported yet.
 *
 * Buffer objects will be allocated using the given buffer size to allow room
 * for driver-specific fields. Driver-specific buffer structures must start
 * with a struct isp_video_buffer field. Drivers with no driver-specific buffer
 * structure must pass the size of the isp_video_buffer structure in the bufsize
 * parameter.
 *
 * Return 0 on success.
 */
int omap3isp_video_queue_init(struct isp_video_queue *queue,
                              enum v4l2_buf_type type,
                              const struct isp_video_queue_operations *ops,
                              struct device *dev, unsigned int bufsize)
{
        INIT_LIST_HEAD(&queue->queue);
        mutex_init(&queue->lock);
        spin_lock_init(&queue->irqlock);

        queue->type = type;
        queue->ops = ops;
        queue->dev = dev;
        queue->bufsize = bufsize;

        return 0;
}

/* -----------------------------------------------------------------------------
 * V4L2 operations
 */

/**
 * omap3isp_video_queue_reqbufs - Allocate video buffers memory
 *
 * This function is intended to be used as a VIDIOC_REQBUFS ioctl handler. It
 * allocated video buffer objects and, for MMAP buffers, buffer memory.
 *
 * If the number of buffers is 0, all buffers are freed and the function returns
 * without performing any allocation.
 *
 * If the number of buffers is not 0, currently allocated buffers (if any) are
 * freed and the requested number of buffers are allocated. Depending on
 * driver-specific requirements and on memory availability, a number of buffer
 * smaller or bigger than requested can be allocated. This isn't considered as
 * an error.
 *
 * Return 0 on success or one of the following error codes:
 *
 * -EINVAL if the buffer type or index are invalid
 * -EBUSY if the queue is busy (streaming or buffers mapped)
 * -ENOMEM if the buffers can't be allocated due to an out-of-memory condition
 */
int omap3isp_video_queue_reqbufs(struct isp_video_queue *queue,
                                 struct v4l2_requestbuffers *rb)
{
        unsigned int nbuffers = rb->count;
        unsigned int size;
        int ret;

        if (rb->type != queue->type)
                return -EINVAL;

        queue->ops->queue_prepare(queue, &nbuffers, &size);
        if (size == 0)
                return -EINVAL;

        nbuffers = min_t(unsigned int, nbuffers, ISP_VIDEO_MAX_BUFFERS);

        mutex_lock(&queue->lock);

        ret = isp_video_queue_alloc(queue, nbuffers, size, rb->memory);
        if (ret < 0)
                goto done;

        rb->count = ret;
        ret = 0;

done:
        mutex_unlock(&queue->lock);
        return ret;
}

/**
 * omap3isp_video_queue_querybuf - Query the status of a buffer in a queue
 *
 * This function is intended to be used as a VIDIOC_QUERYBUF ioctl handler. It
 * returns the status of a given video buffer.
 *
 * Return 0 on success or -EINVAL if the buffer type or index are invalid.
 */
int omap3isp_video_queue_querybuf(struct isp_video_queue *queue,
                                  struct v4l2_buffer *vbuf)
{
        struct isp_video_buffer *buf;
        int ret = 0;

        if (vbuf->type != queue->type)
                return -EINVAL;

        mutex_lock(&queue->lock);

        if (vbuf->index >= queue->count) {
                ret = -EINVAL;
                goto done;
        }

        buf = queue->buffers[vbuf->index];
        isp_video_buffer_query(buf, vbuf);

done:
        mutex_unlock(&queue->lock);
        return ret;
}

/**
 * omap3isp_video_queue_qbuf - Queue a buffer
 *
 * This function is intended to be used as a VIDIOC_QBUF ioctl handler.
 *
 * The v4l2_buffer structure passed from userspace is first sanity tested. If
 * sane, the buffer is then processed and added to the main queue and, if the
 * queue is streaming, to the IRQ queue.
 *
 * Before being enqueued, USERPTR buffers are checked for address changes. If
 * the buffer has a different userspace address, the old memory area is unlocked
 * and the new memory area is locked.
 */
int omap3isp_video_queue_qbuf(struct isp_video_queue *queue,
                              struct v4l2_buffer *vbuf)
{
        struct isp_video_buffer *buf;
        unsigned long flags;
        int ret = -EINVAL;

        if (vbuf->type != queue->type)
                goto done;

        mutex_lock(&queue->lock);

        if (vbuf->index >= queue->count)
                goto done;

        buf = queue->buffers[vbuf->index];

        if (vbuf->memory != buf->vbuf.memory)
                goto done;

        if (buf->state != ISP_BUF_STATE_IDLE)
                goto done;

        if (vbuf->memory == V4L2_MEMORY_USERPTR &&
            vbuf->length < buf->vbuf.length)
                goto done;

        if (vbuf->memory == V4L2_MEMORY_USERPTR &&
            vbuf->m.userptr != buf->vbuf.m.userptr) {
                isp_video_buffer_cleanup(buf);
                buf->vbuf.m.userptr = vbuf->m.userptr;
                buf->prepared = 0;
        }

        if (!buf->prepared) {
                ret = isp_video_buffer_prepare(buf);
                if (ret < 0)
                        goto done;
                buf->prepared = 1;
        }

        isp_video_buffer_cache_sync(buf);

        buf->state = ISP_BUF_STATE_QUEUED;
        list_add_tail(&buf->stream, &queue->queue);

        if (queue->streaming) {
                spin_lock_irqsave(&queue->irqlock, flags);
                queue->ops->buffer_queue(buf);
                spin_unlock_irqrestore(&queue->irqlock, flags);
        }

        ret = 0;

done:
        mutex_unlock(&queue->lock);
        return ret;
}

/**
 * omap3isp_video_queue_dqbuf - Dequeue a buffer
 *
 * This function is intended to be used as a VIDIOC_DQBUF ioctl handler.
 *
 * The v4l2_buffer structure passed from userspace is first sanity tested. If
 * sane, the buffer is then processed and added to the main queue and, if the
 * queue is streaming, to the IRQ queue.
 *
 * Before being enqueued, USERPTR buffers are checked for address changes. If
 * the buffer has a different userspace address, the old memory area is unlocked
 * and the new memory area is locked.
 */
int omap3isp_video_queue_dqbuf(struct isp_video_queue *queue,
                               struct v4l2_buffer *vbuf, int nonblocking)
{
        struct isp_video_buffer *buf;
        int ret;

        if (vbuf->type != queue->type)
                return -EINVAL;

        mutex_lock(&queue->lock);

        if (list_empty(&queue->queue)) {
                ret = -EINVAL;
                goto done;
        }

        buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);
        ret = isp_video_buffer_wait(buf, nonblocking);
        if (ret < 0)
                goto done;

        list_del(&buf->stream);

        isp_video_buffer_query(buf, vbuf);
        buf->state = ISP_BUF_STATE_IDLE;
        vbuf->flags &= ~V4L2_BUF_FLAG_QUEUED;

done:
        mutex_unlock(&queue->lock);
        return ret;
}

/**
 * omap3isp_video_queue_streamon - Start streaming
 *
 * This function is intended to be used as a VIDIOC_STREAMON ioctl handler. It
 * starts streaming on the queue and calls the buffer_queue operation for all
 * queued buffers.
 *
 * Return 0 on success.
 */
int omap3isp_video_queue_streamon(struct isp_video_queue *queue)
{
        struct isp_video_buffer *buf;
        unsigned long flags;

        mutex_lock(&queue->lock);

        if (queue->streaming)
                goto done;

        queue->streaming = 1;

        spin_lock_irqsave(&queue->irqlock, flags);
        list_for_each_entry(buf, &queue->queue, stream)
                queue->ops->buffer_queue(buf);
        spin_unlock_irqrestore(&queue->irqlock, flags);

done:
        mutex_unlock(&queue->lock);
        return 0;
}

/**
 * omap3isp_video_queue_streamoff - Stop streaming
 *
 * This function is intended to be used as a VIDIOC_STREAMOFF ioctl handler. It
 * stops streaming on the queue and wakes up all the buffers.
 *
 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 * delayed works before calling this function to make sure no buffer will be
 * touched by the driver and/or hardware.
 */
void omap3isp_video_queue_streamoff(struct isp_video_queue *queue)
{
        struct isp_video_buffer *buf;
        unsigned long flags;
        unsigned int i;

        mutex_lock(&queue->lock);

        if (!queue->streaming)

                goto done;

        queue->streaming = 0;

        spin_lock_irqsave(&queue->irqlock, flags);
        for (i = 0; i < queue->count; ++i) {
                buf = queue->buffers[i];

                if (buf->state == ISP_BUF_STATE_ACTIVE)
                        wake_up(&buf->wait);

                buf->state = ISP_BUF_STATE_IDLE;
        }
        spin_unlock_irqrestore(&queue->irqlock, flags);

        INIT_LIST_HEAD(&queue->queue);

done:
        mutex_unlock(&queue->lock);
}

/**
 * omap3isp_video_queue_discard_done - Discard all buffers marked as DONE
 *
 * This function is intended to be used with suspend/resume operations. It
 * discards all 'done' buffers as they would be too old to be requested after
 * resume.
 *
 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 * delayed works before calling this function to make sure no buffer will be
 * touched by the driver and/or hardware.
 */
void omap3isp_video_queue_discard_done(struct isp_video_queue *queue)
{
        struct isp_video_buffer *buf;
        unsigned int i;

        mutex_lock(&queue->lock);

        if (!queue->streaming)
                goto done;

        for (i = 0; i < queue->count; ++i) {
                buf = queue->buffers[i];

                if (buf->state == ISP_BUF_STATE_DONE)
                        buf->state = ISP_BUF_STATE_ERROR;
        }

done:
        mutex_unlock(&queue->lock);
}

static void isp_video_queue_vm_open(struct vm_area_struct *vma)
{
        struct isp_video_buffer *buf = vma->vm_private_data;

        buf->vma_use_count++;
}

static void isp_video_queue_vm_close(struct vm_area_struct *vma)
{
        struct isp_video_buffer *buf = vma->vm_private_data;

        buf->vma_use_count--;
}

static const struct vm_operations_struct isp_video_queue_vm_ops = {
        .open = isp_video_queue_vm_open,
        .close = isp_video_queue_vm_close,
};

/**
 * omap3isp_video_queue_mmap - Map buffers to userspace
 *
 * This function is intended to be used as an mmap() file operation handler. It
 * maps a buffer to userspace based on the VMA offset.
 *
 * Only buffers of memory type MMAP are supported.
 */
int omap3isp_video_queue_mmap(struct isp_video_queue *queue,
                         struct vm_area_struct *vma)
{
        struct isp_video_buffer *uninitialized_var(buf);
        unsigned long size;
        unsigned int i;
        int ret = 0;

        mutex_lock(&queue->lock);

        for (i = 0; i < queue->count; ++i) {
                buf = queue->buffers[i];
                if ((buf->vbuf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
                        break;
        }

        if (i == queue->count) {
                ret = -EINVAL;
                goto done;
        }

        size = vma->vm_end - vma->vm_start;

        if (buf->vbuf.memory != V4L2_MEMORY_MMAP ||
            size != PAGE_ALIGN(buf->vbuf.length)) {
                ret = -EINVAL;
                goto done;
        }

        ret = remap_vmalloc_range(vma, buf->vaddr, 0);
        if (ret < 0)
                goto done;

        vma->vm_ops = &isp_video_queue_vm_ops;
        vma->vm_private_data = buf;
        isp_video_queue_vm_open(vma);

done:
        mutex_unlock(&queue->lock);
        return ret;
}

/**
 * omap3isp_video_queue_poll - Poll video queue state
 *
 * This function is intended to be used as a poll() file operation handler. It
 * polls the state of the video buffer at the front of the queue and returns an
 * events mask.
 *
 * If no buffer is present at the front of the queue, POLLERR is returned.
 */
unsigned int omap3isp_video_queue_poll(struct isp_video_queue *queue,
                                       struct file *file, poll_table *wait)
{
        struct isp_video_buffer *buf;
        unsigned int mask = 0;

        mutex_lock(&queue->lock);
        if (list_empty(&queue->queue)) {
                mask |= POLLERR;
                goto done;
        }
        buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);

        poll_wait(file, &buf->wait, wait);
        if (buf->state == ISP_BUF_STATE_DONE ||
            buf->state == ISP_BUF_STATE_ERROR) {
                if (queue->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
                        mask |= POLLIN | POLLRDNORM;
                else
                        mask |= POLLOUT | POLLWRNORM;
        }

done:
        mutex_unlock(&queue->lock);
        return mask;
}